Optical head and optical information medium driving device

Abstract

A semiconductor laser; a light flux separation element that separates a light flux emitted from the semiconductor laser for a first light flux and a second light flux to come out therefrom; an objective lens on which the first light flux coming out from the light flux separation element is incident to be collected on a optical information recording medium; a light-receiving element on which the second light flux coming out from the light flux separation element is incident; an arithmetic circuit that adjusts a quantity of light emitted from the light source in response to a quantity of light incident on the light-receiving element, are provided. A light exiting-surface of the light flux separation element from which the second light flux comes out is laminated to a light incident-surface of the light-receiving element on which the second light flux is incident via an adhesive layer. It is thus possible to adjust a quantity of light at a higher degree of accuracy and higher sensitivity while achieving a significant reduction of the optical head in size.

1 - 14 . (canceled)  
     
     
         15 . An optical head, comprising: 
 a light source;    a light flux separation element that separates a light flux emitted from the light source for at least a first light flux and a second light flux to come out therefrom;    an objective lens on which the first light flux is incident to be collected on an optical information recording medium;    a light-receiving element on which the second light flux is incident;    an arithmetic circuit that adjusts a quantity of light emitted from the light source in response to a quantity of light incident on the light-receiving element; and    a photo-detector on which reflected light from the optical information medium is incident,    wherein a light exiting-surface of the light flux separation element from which the second light flux comes out is laminated to a light incident-surface of the light-receiving element on which the second light flux is incident.    
     
     
         16 . The optical head according to  claim 15 , wherein: 
 the light exiting-surface of the light flux separation element from which the second light flux comes out is laminated to the light incident-surface of the light-receiving element on which the second light flux is incident via a adhesive layer.    
     
     
         17 . The optical head according to  claim 16 , wherein: 
 the adhesive layer has light transmittance of 95% or below.    
     
     
         18 . The optical head according to  claim 17 , wherein: 
 the adhesive layer has the light transmittance of 40% or above.    
     
     
         19 . The optical head according to  claim 17 , wherein: 
 the adhesive layer has the light transmittance of 80% or below.    
     
     
         20 . The optical head according to  claim 19 , wherein: 
 the adhesive has the light transmittance of 60% or above.    
     
     
         21 . The optical head according to  claim 16 , wherein: 
 transmission wave aberration of the adhesive layer is set to 20 mλ or larger.    
     
     
         22 . The optical head according to  claim 21 , wherein: 
 transmission wave aberration of the adhesive layer is set to 300 mλ or smaller.    
     
     
         23 . The optical head according to  claim 21 , wherein: 
 transmission wave aberration of the adhesive layer is set to 60 mλ or larger.    
     
     
         24 . The optical head according to  claim 23 , wherein: 
 transmission wave aberration of the adhesive layer is set to 200 mλ or smaller.    
     
     
         25 . The optical head according to  claim 16 , wherein: 
 the adhesive layer is made of UV-curing adhesive.    
     
     
         26 . The optical head according to  claim 15 , further comprising: 
 an objective lens moving mechanism that moves the objective lens in a focus direction and in a tracking direction, wherein:    the objective lens moving mechanism includes a holder that holds the objective lens to be movable in the focus direction and in the tracking direction, and a base that supports the holder; and    the light flux separation element is disposed so as to be set inside the base.    
     
     
         27 . The optical head according to  claim 26 , wherein: 
 the light-receiving element is disposed so as to be set inside the base together with the light flux separation element.    
     
     
         28 . An optical information medium driving device, comprising: 
 an optical head;    a focus control circuit that controls the optical head on the basis of a focus error signal obtained from the optical head; and    a tracking control circuit that controls the optical head on the basis of a tracking error signal obtained from the optical head,    the optical head including:    a light source;    a light flux separation element that separates a light flux emitted from the light source for at least a first light flux and a second light flux to come out therefrom;    an objective lens on which the first light flux is incident to be collected on an optical information recording medium;    a light-receiving element on which the second light flux is incident;    an arithmetic circuit that adjusts a quantity of light emitted from the light source in response to a quantity of light incident on the light-receiving element; and    a photo-detector on which reflected light from the optical information medium is incident,    wherein a light exiting-surface of the light flux separation element from which the second light flux comes out is laminated to a light incident-surface of the light-receiving element on which the second light flux is incident.